Device and process for thickening and conveying waste water sludge

ABSTRACT

The present invention relates to a device and a process for thickening and conveying waste water sludges, especially with a centrifuge. Here, the centrifuge has at least one lysis device for the breaking down of cells of organisms contained in the waste water sludges. The lysis device of the device of the invention may take the form, for example, of a friction grinder (100; 200) with grinding discs (161, 162) or a milling cone, a shaped rasp, a roller crusher, a passing drum, a cutting unit with rows of rotary cutters or a pin grinder with rows of rotating pins. The device of the invention is capable of the lysis of cells, especially those of bacteria and protozoons so that their cell content discharges into the surrounding medium which then acts as a simulation reagent for the bacteria still present in the sludge, so that on the one hand the total quantity of sludge can be greatly reduced and on the other the bio-gas yield is considerably increased.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a device for thickening of waste watersludges, a sewage treatment or waste-water purification plant (hereafterwaste-water treatment plant), a process for minimizing the amount ofdecomposed sludge or, as the case may be, the residual sludge inpurification plants, as well as a device for treatment of waste water.

The inventive device as well as the inventive process serve to minimizeor reduce the amount of sludge produced in purification plants, toimprove dewatering, and to accelerate the bio-gas fermentation during ananaerobic methane fermentation of the sludge, the waste biomass, as wellas during the anaerobic purification of waste water.

In the process of biological purification of waste a relatively largeamount of sludge is produced, wherein the handling thereof and theeconomical use often leads to problems. In the aerobic biologicpurification of the waste water at least two types of sludges areproduced; primary sludge--that sludge which is produced by the primarysedimentation or settling of the introduced waste water and whichexperiences a rapid decomposition--and as the second sludge type theactivated surplus sludge, which results after the step of the biologicalpurification of the waste water. Herein primarily a mixture ofmicroorganisms takes part, which are produced during the waste waterpurification and of which the count depends upon the of the number ofthe impurities removed as well as on the parameters of the processduring purification. Both sludge types are processed in most waste-watertreatment plants, above all the larger ones, by an anaerobic methanefermentation.

The anaerobic methane fermentation of organic substances is a process,in which a mixed culture of microorganisms stepwise decomposes abiologically decomposable organic mass under anaerobic conditions. Theend products of this decomposition are methane, carbon dioxide, sulfurdioxide (Sulfan), nitrogen, hydrogen, the resulting biomass and astabilized organic material (a residual which is not furtherdecomposable).

Among the most important factors which influence the process of theanaerobic decomposition, there are included the composition of thesubstrate (which determines the specific production as well as thecomposition of the bio-gas), the presence of nutrients, the pH-value,the buffer capacity as well as the temperature. The economicalfeasibility of this process is dependent upon the dry substanceconcentration (solid substance concentration) of the material to beprocessed. For this reason the starting materials are frequentlysubjected to a thickening process, wherein this occurs eithermechanically (centrifuge, press, among others) or with the aid ofgravity.

For an optimal progress of the anaerobic decomposition the presence of aseries of an organic nutrients is of consequence. The presence of aseries of growth factors (reproductive factors) is important as well asvitamins and enzymes. For anaerobic decomposition, above all hydrolyticenzymes are of importance, which are capable of decomposing or reducinga large number of substances such as, for example, even solid and highmolecular organic substances. Several of these materials can besynthesized by the microorganisms themselves, others must be added fromoutside the system.

2. Description of the Related Art

A laboratory or bench top possibility for simulating the bio-gasproduction during anaerobic methane fermentation of sludges, wastewater, as well as other various organic materials is described in CZ-PS242 979. The process disclosed in this patent is comprised therein, thatthe material to be fermented has added to it, or in given cases theanaerobic reactor has added directly to it, a stimulating material whichis prepared separate from the laboratory waste water purification systemand which is a mechanically or physically treatedmicroorganism-containing biomass suspension of between 0.1 up to 10weight-%, preferably 5 weight-%, depending upon the organic drysubstance of the material to be processed.

In the lytic treatment (mechanical and physical disruption of cells) ofthe biomass suspension according to the state of the art the content ofthe cells of these microorganisms is partially set free.

The content of the microorganism cells or cells of other organisms whichin the course of the destruction of cell walls and/or cell membranes arereleased into the solution (also called cell lysate), has a facilitatingor stimulating effect upon the process of biological decomposition ofthe organic substances. The lysate of the cells occurs on the one handin a natural way (autolysis) with deceased cells, on the other hand withthe help of hydrolytic enzymes, which are released into the solution byfermentation bacteria, and further by the artificial decomposition ordissociation of microorganisms or organisms with the help ofphysico-chemical or mechanical methods.

The cell lysate stimulates on the one hand the function and the growthof microorganisms, on the other hand it contains a series of enzymes,which are directly necessary for the decomposition of organicsubstances. The lysate stimulates the functionality or operability ofcertain bacteria, which convert and/or release hydrogen and carbondioxide, acetic acids, propionic acids, etc. Besides this it strengthensthe decomposition of organic materials and increases the bio-gasproduction in anaerobic methane producing processes which has as aconsequence a reduction of the total amount of the produced sludge aswell as an increase in the bio-gas production. The cell lysate canlikewise significantly influence the production of surplus activatedsludge when using activation tanks.

The preparation of cell lysate in laboratory scale amounts according tothe state of the art is expenfiltere in terms of the equipment necessarytherefor as well as the required amount of energy. This is true for thehitherto known methods of cell decomposition or destruction such as, forexample, in the disruption by means of mechanical methods (grinding,milling, pressing), sonification (ultra sound treatment), cavitation,repeated freezing and thawing, heating, among others.

The above described process according to the state of the art asdescribed in CZ-PS 242 979 has above all the disadvantage, that itrequires a separate preparation of the cell lysate -external of theactual purification or treatment device. As already mentioned above,this process is only suitable on a laboratory scale; a transition to anindustrial scale process is not practicable for reasons of the largespace requirement, the high energy cost and investiture cost and theadditional personnel requirement. So it is, for example, neithereconomical nor technically useful to cyclically freeze and then thawsludge in amounts which are measured in tons.

With the state of the art as described in CZ-PS 242 979 as a startingpoint, it is the task of the present invention to significantly reducethe sludge amount yielded under industrial scale conditions in a lessexpenfiltere and in a more economical manner.

SUMMARY OF THE INVENTION

The present invention provides a device for thickening and/or conveyingwaste water sludge, in particular surplus sludge. In its construction itis so designed that the cells of the organisms contained in theclarified sludge, in particular microorganisms, are at least partiallylysed during the thickening.

By means of the inventive device the sludge produced in the purificationplant is significantly reduced. Further, due to the fact that the cellsof the microorganisms are lysed in the thickening device, it becomespossible to employ this device also in the realm of large scale.

As to industrial processing engineering, this occurs as alreadydescribed in the German Patent Application 195 02 856.2 of the sameapplicant with the title "Device and Process for Reduction of SludgeProducts in Purification Plants" of Jan. 30, 1995, the entirety of whichis incorporated herein by reference. Reference is likewise made to theGerman Patent Application 195 27 784.8 of the same applicant entitled"Device for Thickening and Promoting of Waste Water Sludges" of Jul. 28,1995, which is likewise completely incorporated herein by reference.

Thereby there is evolved a particular advantage, that the thickeningapparatus can be employed to serve simultaneously for thickening and/orconveyance of sludge as well also for lysis of the cells, which makesthe apparatus or the process economical. Beyond this there is inaccordance with the inventive devices the possibility of continuouslysing of the cells at a relatively minimal sludge throughput, wherebyit is avoided, that large sludge amounts must be processed at once.

Alternatively to the inventive thickening device in particular one witha centrifuge, which includes a lysing device, the cumulative variousadvantages of the invention can also be achieved also with a conveyingdevice in particular a pump, which includes a lysing device. The lysingdevice therein is essentially similar in construction to the lysingdevice of the inventive assembly.

The purification plant according to the invention for waste waterscomprises at least a settling tank with at least one effluent input; atleast one conveyance device; at least one aerobic activation device; atleast one thickening unit, which yields surplus sludge; and at least oneanaerobic reactor and is thereby characterized, that the thickeningdevice and/or conveyance device is so constructed, that the cells of themicroorganisms contained in the surplus sludge are at least partiallylysed during the thickening and/or conveyance.

Finally in accordance with the invention there is provided a process forreduction of sludge amounts or as the case may be residual sludge inpurification plants, which comprises the following steps:

Allowing waste water to settle in at least one settling tank andconveying the settled or sedimented surplus sludge to least oneanaerobic reactor by means of at least one conveyance device as well asfurther conveyance of the waste water into an aerobic activation unit ordevice;

aerobic conversion of the waste water after settling in at least oneaerobic activation unit;

thickening of the surplus sludge in at least one thickening device orunit;

conversion of the surplus sludge in at least one anaerobic reactor;wherein

the microorganisms contained in the surplus sludge from the thickeningdevice and/or waste water are at least partially lysed in the thickeningdevice and/or in the conveyance device prior to the decomposition tower.

By using the inventive device or the process according to the invention,the sludge production in treatment plants can be significantly reduced.As a result of the fact that the cells of the microorganisms arethemselves lysed in the treatment device or, as the case may be, in thethickening and/or conveyance device, it is besides this possible, toutilize these devices or this process also in the large scaleenvironment. Thereby an advantage is produced, that the thickeningand/or conveyance device is simultaneously used for thickening and/orconveying the sludge as well also as for lysis of the cells, which makesthe device or the process more economical. Beyond this it is possible inthe device or, as the case may be, the process, to continuously lyse thecells with a relatively small sludge throughput, whereby it is avoided,that large sludge amounts must be simultaneously processed.

Since in the inventive device or, as the case may be, the inventiveprocess, there is no longer any requirement for expenfiltere preparationof cell lysate outside of the purification plant, there aresimultaneously achieved the advantages of no increased costs and noincreased energy and personnel requirements. Besides this the efficiencyor output of the anaerobic reactor is increased and the decomposition oforganic substances is accelerated, problematic substances or compoundssuch as for example various xenobiotica or poison substances are moreintensely decomposed, the production of combustible gas is increased andthe energy balance sheet is improved as compared to the state of theart.

The above indicated disadvantages of the state of the art are overcomeby the device according to the invention or, as the case may be, thepurification plant according to the invention, wherein the treatment ofsludge and waste biomass is accomplished by anaerobic methanefermentation as well as in the anaerobic waste water purification.

The present invention encompasses a device for thickening of waste watersludge with a centrifuge, wherein the centrifuge is provided with atleast one lysing device for breaking open the cells of the organismscontained in the waste water sludge as well as a device for conveyanceof sludge containing waste water with at least one such lysing device.

In the preferred embodiment of the present invention the lysing deviceis an integral component of the centrifuge or as the case may be theconveyance device, in particular a pump, and is preferably provided atthe centrifuge exit side or, as the case may be, pump output side.

Of course a separate lysing device can however be provided on either thecentrifuge input or, as the case may be, at the conveyance device input,as well as at the centrifuge output or, as the case may be, conveyancedevice output or in the conduit system independent of a directconstructional coupling with the centrifuge and/or the conveyancedevice.

The particular advantage of the present invention lies founded therein,that the present invention can be incorporated in the thickening devicesaccording to the existing conventional waste water technology, inparticular centrifuges or as the case may be conveyance devices, inparticular pumps, whereby only a relatively small constructionmodification must occur, in order for them to meet the conditions of thepresent invention.

The device is essentially characterized therein, that it has a higherlevel of conveyancing and thickening effectiveness, when it includes arotating conveyor screw as well as a rotating jacket, wherein therotating jacket essentially provides a better conveyancing of the sludgeand substantially prevents a coating or caking of the conveyer screw tothe jacket of the centrifuge.

This effect is thereby strengthened, that the screw conveyor device andthe jacket of the centrifuge rotate with different rotational speeds.

The rotational speed of the screw conveyor lies at approximately 10 RPMhigher than the rotational speed of the centrifugal jacket.

The lysis device can, as already discussed above, be provided at thecentrifuge input and/or centrifuge output and/or integrated in thecentrifuge. This has the advantage, that hereby a variety of measuresare made available, for adapting or fitting the present invention to thevarious conditions and constituencies and compositions of the wastewater sludges in the various treatment plants.

In order to keep larger foreign bodies from the naturally relativelynarrow entryway and passage spaces within the lysing device, it isfrequently useful to provide a sieve device in the sludge introductionside for the lysing device. By this means the damaging of the lysingdevice by larger materials such as stones and non- decomposable wastematerials is substantially prevented.

This type of filter device is preferably provided in such a manner, thatit is easily changed out during the operation of the treatment plant andthe centrifuge. Accordingly, there is for example envisioned thepossibility of a bifurcated sludge input in the form of a bypass,wherein the sludge path can be conducted through the bypass with intactfilter device, when the filter device of the other pathway must becleansed. The lysing device itself can be constructed in a number ofways. Whichever specific lysing device is to be selected depends uponthe respective sludge conditions, so that here a wide selection isavailable as to which centrifuges are to be combined with which lysingdevices for which purpose.

Conveyance devices can be employed, which combine conventional pumpswith a lysing device in accordance with the present invention.

At the present time experience has been had with seven different lysingdevices.

So there is a lysing device constructed for example as a frictiongrinding unit, which means, that basically shearing and rubbing forcesin the manner of a grinder using a mill stone is responsible for thelysing effect.

Such a friction grinding unit as lysing device is provided at theinventive device, wherein this friction grinding unit is comprised of atleast one grinding disk, which serves for grinding of the sludge and thetherein contained cells.

In such a device the sludge which has been de-watered by the centrifugeis preferably mechanically rubbed between two roughened surfaces,wherein due to the high shear force, which occur within the sludge andthe cells between the rubbing surfaces, the cells of the microorganismsand higher organisms are ruptured and therewith lysed.

Preferably such a frictional grinding unit is constructed as lysingdevice, wherein a grinding disk is connected with the rotating jacket ofthe centrifuge and rotates along with this and moves against anadditional stationary grinding disk. Herein the separation between thegrinding disks is in the range of 0.5-5 mm.

A construction of this type of a lysing device has the advantage, thatit is achieved with little sealing requirement, that the space betweenthe two grinding disks is adjustable whereby the degree of lysing isadjustable, and that a lysing device of this type is also capable ofbeing constructed to provide multiple stages, wherein varying surfacesof the grinding disks or as the case may be, varying spatial separationsbetween the grinding disks of the individual stages can be made.

On the basis of the relatively small gap between the two grinding disks,it is worthwhile to take measures to retain larger foreign bodies withinthe sludge by a filter at the input or feeder side, in order to preventdamage to the lysing device.

An increasing of the shear forces, which impact upon the cells containedin the waste water, is particularly caused thereby, that the grindingdisks have recesses on their grinding surfaces, in particular notches,wherein these notches have an angle of incidence or angle of attack withrespect to the radial direction. Therein it is particularly preferred,that these recesses are provided in the rotating grinding disk, sincethereby a kind of pumping effect as well as a formation of relativelylarge pressure gradients and therewith a increased shear and therebynecessarily a increased lysing effect is brought about.

When angles of attack of the recesses or as the case may be notches areoriented with respect to the radial direction of the outer surface ofthe grinding disk, preferably the rotating grinding disk, the pumpingeffect can be increased or weakened in accordance with the angles.

The provision of staggered adjacent lying rows of notches has theadvantage, that the sheering effect and the associated lysing effect isfurther strengthened also by the production of turbulence.

The residence time of the sludge in this type of lysing device can alsobe controlled thereby, that a dam or gate can be provided at the sludgeexit, of which the height controls the volume of sludge in the lysingdevice and therewith the residence time.

Hereby the lysing efficiency can be controlled according to requirementsand varied or as the case may be manipulated or adjusted.

A further type of a inventive device has a lysing device, which islikewise designed as a friction grinding unit, however in place of agrinding disk, a milling cone is provided for grinding the sludge andthe therein contained cells.

The lysing effect as produced herein is similar to the above describedembodiment of the inventive device, namely, at the output of thecentrifuge and/or conveyance device, the sludge enters likewise in themilling cone and is rubbed between the rotating external cone, which hasat least one grinding surface, and a preferably stationary inner cone. Akinematic reversal is also possible. The rotating external cone as wellalso as the stationary internal cone can, as necessary, be provided withsurface recesses and in particular notches, which are here preferablyprovided in the direction of the jacket line of the grinding cone or ata angle of attack thereto, wherein these recesses have the same lysingstrengthening effect as the recesses on the grinding disk in the abovedescribed embodiment.

Particularly preferred is, in the illustrative embodiment of the presentinvention, which employs a grinding cone as lysing device, that thecleft between rotating outer cone and the stationary inner cone is incertain conditions during operation capable of being varied and adjustedvia a stop or detent and springs.

The embodiment of the device according to the invention which employs agrinding cone as a lysing device has the advantage that it is simple toadjust and that it can yield to large foreign bodies as a result of thespring mounting of the inner cone.

The inventive device for thickening of waste water sludge is providedwith a so-called shape or profile rasp as the lysing device. In thisprofile rasp there is provided a stationary outer hull and a rotatingrasp surface which is connected with the rotating jacket of thecentrifuge, whereby a narrow cleft exists between the stationary outerhull and the rasp surface.

Sludge, which enters through an opening between the rotating raspsurface into the cleft between outer hull and rasp surface, is forced toflow into this narrow spatial separation, whereby the great pressurecauses such high sheer forces to be produced that the cell walls ofbacteria and other microorganisms such as for example protozoa burst andtherewith are lysed.

The rotating rasp surface can have on its upper surface recesses, inparticular wave shaped recesses, which further serve to increase thesheer forces.

The rasp surfaces can be provided on both sides of their exit openingwith varying pitches or inclinations in the direction of the outercasing or shell, whereby that respective part of the rasp surface, whichis directed towards the closed end of the device is narrower than thatrespective part of the rasp surface which is directed towards the sludgeoutput opening, whereby a pressure gradient in the direction of thesludge outlet results.

As a result of the pressure gradient there is, on the one hand, aconveyance effect in the direction of the sludge exit achieved and, onthe other hand, the shear forces working on the microorganisms are againincreased, whereby the lysing effect is overall strengthened.

The sludge supply side for the profile rasp is preferably providedcentrally and exhibits a space between rubbing surface and outer shellof at least 1 mm to maximal 10 mm.

The construction of the lysing device as a profile rasp has overall theadvantage, that practically no sealing problems occur, that it is simpleto construct, that no metal rubbing occurs and that larger particles canbe shunted away, so that in given cases a filter or filter device can bedispensed with.

Beyond this the construction height in an industrial construction can bekept low so that a relative space saving construction is made possible.

The mechanism of lysing is achieved primarily by squashing and rubbingand the thereby resulting sheer forces.

A further embodiment of the present device for thickening of waste watersludge or, as the case may be, conveying device is disclosed, namely,one such device, with which the lysing device is provided as a roller orcylinder press.

In this embodiment of the inventive device, rollers are rolled in themanner of a roller bearing element upon the inner wall of a stationaryouter shell by a rotating part, in the internal part rotating direction.Here in practice a stationary outer cylinder is provided, which hasrecesses in which the rollers can move. Beyond this the rotating part,which is connected to the jacket of the centrifuge, is likewise providedwith recesses, in which a different set of rollers is mounted and viawhich are rolled over the inside outer circumference of the outer shellin the inside circumference rotating direction.

When sludge enters from the centrifuge output into such a lysing device,it enters into the internal space of the rollers and is taken alongtherewith, is rolled over and thus squashed, wherein high sheer forcesoccur which are sufficient to lyse the cells of the organisms containedin the waste water, in particular microorganisms, and in particular tofinely lyse these.

One roller set is comprised of at least ten rollers, wherein a total ofat least two roller sets are preferred.

A device according to the invention with a roller crusher as lysingdevice provides a good squashing and lysing effect, wherein theconstruction height can be maintained relatively low.

For a lysing device of this type however a relatively high precision isrequired in the construction of the individual parts as well as arelatively high running quietness is demanded, since even small mineralparticles can eat at the device, so that a filter is preferably providedin this lysing device prior to the centrifuge.

A device for thickening of waste water sludges or, as the case may be, adevice for conveying of sludge containing waste waters, in which thelysing device is constructed as a so called passing or paddle bladedrum.

A passing drum of this type is comprised of multiple passing elements,which rotate within a stationary outer shell with a preferablyadjustable spacing with respect to the inner wall of the outer shell. Ifsludge from the centrifugal input is supplied between the individualpassing elements, then it is squashed by the narrow space between theouter shell and the individual passing elements which can be constructedfor example as passing disks or blades, and the microorganism cells aredisrupted by the thereby resulting high sheer forces.

The advantage of this type of lysing device lies founded therein that avery small construction space is possible and that multiple lysingdevices of this type can be coupled one after the other in order toincrease the lysing effect, preferably step-wise.

Since in the construction of the lysing device of this type howeverlarge foreign bodies can lead to damage to the passing elements, it isworthwhile to use a filter to remove larger foreign bodies prior to thecentrifuge.

A device for thickening of waste water sludge or, as the case may be,conveying is addressed, which comprises a cutting unit as lysing device.

A cutting unit of this type is comprised of rotating rows of cuttingelements, in particular knife rows, stationary cutting elements, inparticular knife rows, as well as a dam at the sludge outlet of thelysing device, and the cutting elements are provided such that theyinterdigitate with each other without however contacting each other.

As a rule the sludge from the centrifuge output enters into the innerworkings of the cutting device wherein the sludge leaves the centrifugeat approximately 50 m/s and then first impacts upon an inclined orcanted surface, whereby already a portion of the cells are disrupted asa result of the impact impulse. The sludge is further conveyed via acanal or channel in the cutting unit where it is pressed through andsubject to a multiplicity of rotating knives on the one hand andstationary knives on the other hand perpendicular to a rotation plane,and the sludge is subjected to enormous shredding and shearing forces bythe cutting elements which are preferably constructed as knives, wherebythe cells, which are contained in the waste water sludge, are lysed. Theprimary physical manner of operation lies thereby in the cutting andimpacting of the cells.

The distance between the rotating and the stationary knife rows may beadjustable, whereby the lysing effect of the cutting unit and thecharacteristics of the sludge can be accommodated.

In practice it has been determined, that the knives rotate with a speedof approximately 50-100 m/s, preferably 80 m/s.

This speed ensures on the one hand a sufficient lysing effect and on theother hand a relatively high surface life or edge life of the cuttingelements.

The knife rows are preferably so staggered that adjacent lying kniferows are so positioned, that regions in which one knife row isinterrupted, there is no interruption in the adjacent knife row, wherebythe lysing effect is significantly strengthened.

A further possibility for increasing the lysing effect lies therein,that the ends of the cutting elements, in particular, the knife ends,have a blade angle or an angle of attack to the rotation direction ofthe cutting unit, so that hereby a part of the sludge is again directedto the previous cutting element row, in particular knife row, so thatessentially a pumping effect in the direction of the centrifuge resultsand hereby the residence time of the sludge within the cutting unit ifdesired can be drastically increased.

The residence time is likewise adjustable by the height of the gate ordam at the sludge outlet.

The advantage of constructing the lysing device of the inventive deviceas a cutting unit lies founded therein, that this type of lysing devicecan be constructed for improving the level of effectiveness of thelysing of the cells of the microorganisms, for example by increasing thenumber of knives or by changing the angle of attack of the knives, sothat an excellent mincing occurs and the residence time is adjustable bymultiple construction parameters, such as for example, dam or gateheight, angle of attack of the knives as well as separation betweenrotating and fixed or stationary cutting elements, length of the cuttingelements in the direction of rotation and height of the knives.

Since the knives as cutting elements are relatively sensitive, it ispreferred that filtering occur for filtering out of larger foreignbodies, preferably already at the centrifuge inlet or in cases at theentrance of the conveyance device.

In order to increase the life of the cutting elements, it is preferredthat hard materials are employed therefore, such as for examplechrome-vanadium-molybdenum-alloys or titanium, as well as tungstencarbide or diamond powder containing cutters.

The device according to the invention encompasses a pin disk mill orgrinder as the lysing device.

Fundamentally, a pin disk grinder of this type is constructed similar tothe cutting unit, however with the difference that no cutting elementsbut rather pins are provided on the rotating and the stationary parts,wherein these pins which are arranged in the form of pin rows engage inone another and wherein the rotating pin rows do not contact with thestationary pin rows.

In this type of lysing device the sludge emitted from the centrifugeoutput or, as the case may be, at the output of the conveyance deviceenters into the inside of the pin mill unit, wherein the sludge isforced through the narrow gaps of the interdigitating and partiallyrotating pins, whereby the cells contained in the sludge are lysed bybeing impacted and smashed. Beyond this, high sheer forces occur betweenthe individual pins, whereby likewise the lysis of cells occurs.

The spacing between the stationary and rotating pin rows is adjustable,whereby the degree of lysing can be adjusted.

The pins rotate with a speed of approximately 50-100 m/s, preferablyapproximately 80 m/s.

Adjacent lying rows of pins are oriented to be staggered so that inareas in which no pins are provided in a pin row the adjacent pin row isprovided with pins. The pins may be provided at an angle to the axis ofrotation. Thereby likewise an increase in the lysing effect can beachieved.

The height of the dam at the sludge outlet can be adjusted or varied inthe lysing device of this type whereby again the residence time of thesludge within the lysing device can be adjusted to meet therequirements.

An inventive device for thickening of waste water sludge or, as the casemay be, for conveying of sludge containing waste water, with a lysingdevice which is constructed as a pin milling or grinding unit has theadvantages, that the residence time is adjustable, that it can beconstructed in a variety of arbitrary manners and that the effect isvery easy to vary for example by altering the number of impacting pins,and that impacting pins are easily changed out as necessary.

It is desirable also in this embodiment that foreign bodies be retainedby a filter or filter device preferably at the centrifuge or, as thecase may be, pump inlet.

A purification plant is addressed which includes at least one settlingtank with at least one affluent (inlet) as well as at least oneconveyance device, at least on aerobic activation device and at leastone anaerobic reactor, wherein the purification plant includes at leastone device for thickening of waste water sludge, in which a lysingdevice is provided.

As lysing device one can employ, besides those already described, also avacuum device and/or pressurization device, in particular a press deviceand/or grinding device and/or acoustic irradiation device, preferably anultrasonic device and/or vibration device. By these variouspossibilities the plant can be adjusted to optimized to fit therequirements of the respective waste water and/or sludge. Further thelysing effect can be strengthened or weakened according to requirements,whereby the device according to the invention or, as the case may be,the therewith carried out process, is very adaptable.

The purification may include a supplemental settling or clarificationtank between the aerobic activation device and the thickening device inorder to improve the purification or clarification. Further thesupplemental clarification tank can also assume the function of astorage unit or act as a buffer.

The aerobic activation unit is preferably connected directly to thesettling tank, which has the advantage of a unitary conveyance systemand a reduced odor capacity.

The conveyance device or, as the case may be, conveyance unit can forexample be a return sludge pump, which is preferably situated downstreamof the supplemental clarification tank and is connected with an input ofthe aerobic activation device. Therewith the aerobic treatment of thewaste water can be further improved. Further the conveyance device canfor example be a paddle wheel device. Also, the conveyance device forconveying the thickened sludge to the anaerobic treatment can beprovided with a lysing device.

Preferably the thickening device of the treatment plant is a centrifugewith a suitable lysing device. This has the advantage, that besides thelysing of cells a substantial de-watering of the sludge can beaccomplished. Therewith simultaneously the potential transport costs ofsludge can be reduced. A further advantage also lies therein, that thewater content of the sludge can be adjusted.

Further, a thickening and/or de-watering device, preferably acentrifuge, can be provided also after the anaerobic reactor, in orderthat the sludge is dried as intensely as possible prior to the finalstorage and/or burning. Here also there results the above describedadvantages of reduced transport costs as well as adjustability of watercontent.

In accordance with the invention at least one device for thickening ofwaste water sludge with a lysing device is employed in the treatmentplant.

The lysing device can thus for example be a friction grinding unit, inparticular, a grinding disk for grinding or a milling cone grindingunit, a profile rasp, a roller crusher, a passing drum, a cutting unitor a pin milling unit.

Of course, also combinations of these lysing unit types can beconsidered in one and the same centrifuge and/or thickening deviceand/or conveyance device or conveyance unit.

Beyond this the purification plant in accordance with the invention canbe employed with multiple centrifuges and/or conveyance devices withrespectively various lysing devices. The advantage hereof lies foundedtherein that the adjustment or the coordination of the lysing device canby such measures be coordinated to the sludge consistency andcomposition.

The aerobic converted waste water can be supplementally clarified in atleast one supplemental clarification tank or reservoir and the purifiedwaste water can be conveyed off and at least a part of the settledclarification sludge can be further conveyed to a thickening device.This has the advantage, that less volume must be further processed,whereby the facility is made more economical.

The anaerobic converted sludge can also be thickened in a furtherthickening device (centrifuge). The cumulative centrate is, after thecentrifuge, conveyed to the aerobic activation device. A part of thecentrate of the centrifuge can be conveyed to the aerobic reactor forstimulation.

Preferably an amount of approximately 0.5-50% of the amount of theoriginally present organism cells are lysed. Therewith the stimulationand/or the resulting sludge amount can be controlled.

Also a portion of the anaerobic converted and/or thickened sludge can bereturned back to the anaerobic reactor, in order that it be furtherdecomposed.

For decomposition (destruction) or as the case may be lysis of a portionof the cells there can for example be used the centrifugal force actingupon the cells during pumping and/or the centrifugation of the materialbeing processed (activated or anaerobic stabilized sludge or, as thecase may be, another biomass).

A further advantage of the process carried out with the purification ortreatment plant according to the invention is that the anaerobic reactorproduces a combustible gas, in particular methane. The combustible gasproduced in the process can be used for production of electricity,wherein the produced electricity is preferably employed directly forpowering the clarification plant and/or feeding directly to anelectrical network.

Further advantages and characteristics of the present invention come tolight on the basis of the description of illustrative embodiments aswell as through the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 an overview of an inventive device in longitudinal section.

FIG. 2 a sectional view of a part of the inventive device with afriction grinding unit lysing device according to a first embodiment.

FIG. 3a a schematic representation of the outer surface of a grinding ormilling disk, which is utilized in the inventive device according to thefirst embodiment;

FIG. 3b a schematic representation of the outer surface recessesaccording to FIG. 3a in an alternative design;

FIG. 4 a sectional view of a part of the inventive device according to asecond embodiment;

FIG. 5 a sectional view of a part of the inventive device according to athird embodiment;

FIG. 6 a sectional view according to the section 6--6 in FIG. 5;

FIG. 7 a sectional view of a part of the inventive device according to afourth embodiment;

FIG. 7a a side section along the line 7--7 in FIG. 7;

FIG. 8 a sectional view of a part of the inventive device according to afifth embodiment;

FIG. 9 a section view along the line 9--9 in FIG. 8;

FIG. 10 a sectional view of a part of the inventive device according toa sixth embodiment;

FIG. 11 a sectional view along the line 11--11 in FIG. 10;

FIG. 12 a sectional view along the line 12--12 in FIG. 10;

FIG. 13 a sectional view of a part of the inventive device according toa seventh embodiment;

FIG. 14 a sectional view along the line 14--14 in FIG. 13; and

FIG. 15 a schematic representation of the embodiment of the inventivetreatment plant.

DETAILED DESCRIPTION OF THE INVENTION

In the following the inventive device is described by reference to acentrifuge with a lysing device. The invention is however is not limitedthereto; rather, any suitable conveyance device for sludge containingwaste water can be combined with the described lysing device and beemployed at various positions within a treatment plant in the sense ofthe present invention.

In FIG. 1 the device for thickening of waste water sludge is indicatedwith 1. The device 1 is comprised of a housing 2, on the inside 3 ofwhich a centrifuge 4 is provided. The centrifuge 4 has on the inside 5thereof a snake or screw conveyor 6 as rotating conveyance device aswell as a rotating jacket 7.

In the thickening of the waste water sludge the treated sludge isconducted via a not shown tube or conduit to a centrifuge entryway 8 ofthe centrifuge 4. The waste water sludge is then conveyed through therotating screw conveyor 6 in the inside 5 of the centrifuge 4 in thedirection of the arrow indicated in FIG. 1 to the back end 9 and finallyto the centrifuge exit. In given cases the screw conveyor 6 rotates witha circumference speed of approximately 3010 RPM and the jacket 7 rotateswith a circumference speed of approximately 3000 RPM, wherein therotational direction of the screw conveyor 6 and the jacket 7 areidentical.

At the back end 9 of the centrifuge 4 there is provided, for example, alysing device 10 within the housing 11.

The lysing device 10 includes a rotating part 12 as well as a stationarypart 13. The rotating part 12 of the lysing device 10 as well as thejacket 7 of the centrifuge 4 are driven via a drive 14.

The screw conveyor 6 and the centrifuge 4 are driven via a second drive,not shown in FIG. 1, for example, a hydraulic drive or via a drive gear.

For obtaining lysate containing sludge, the processed sludge, which isconventionally available in treatment plants, is conveyed via a screwconveyor 6 of the centrifuge 4 to a centrifuge exit 9, in order to haveaccess to the inner 15 of the lysate device 10. Cells of organisms, inparticular microorganisms, such as protozoa and bacteria, as well asalgae and nematodes, as well as components of higher plants, aredestroyed or disrupted in the lysing device 10 or, as the case may be,are lysed, so that their membrane and/or cellular wall is ruptured andthe cellular content is released to the surroundings.

Since naturally not all of the cells present in the sludge are lysed,the cell content of the lysed cells serves as a nutrient for otherorganisms during the treatment technological further processing of thesludge, whereby on the one hand the bio-gas production, in particularmethane production, in the decomposition tower is increasedsubstantially, and wherein conversion of the total sludge mass isreduced dramatically.

In the following there will now be described embodiments of theinventive device with varying lysing devices 10.

FIG. 2 shows a lysing device 100, which is provided to the centrifugeoutput 9 of the centrifuge 4 of a device 1 for thickening of waste watersludges.

The rotating part 120 of the lysing device 100 according to FIG. 2 isconnected with the jacket 7 of the centrifuge 4, so that it rotates withthe jacket 7. The stationary part 130 of the lysing device 100 isconstructed as a stationary cup. In the embodiment according to FIG. 2the lysing device 100 exhibits as a friction grinding device on a partof the outer surface of the rotating part 120 a grinding or milling disk161. The stationary part 130 of the lysing device 100 likewise exhibitsa milling disk 162.

In this exemplary case the milling disk 161 exhibits recesses 163 whichare preferably oriented in the radial direction according to FIG. 3a. Asa result of the rotation of the screw conveyor 6 and the jacket 7 of thecentrifuge 4 the waste water sludge is conveyed in the direction shownin the arrow to the centrifuge exit 9 and transported with a speed ofapproximately 50 m/s into the inside 150 of the lysing device 100. Thesludge must now pass through the cleft 170 where it is ground betweenthe milling surfaces 164 and 165. Thereby the recesses 163, which arepreferably provided in the rotating milling disk 161, are of particularadvantage since they enhance the milling and sheer forces of the lysingdevice 100 and therewith lead to a increased cell lysing.

After the sludge has been ground in cleft 170, it collects as a resultof the centrifugal force in the upper end 180 of the lysing device 100shown in FIG. 2. The sludge height and therewith the cumulativeresidence time of the sludge in the lysing device 100 is determined onthe one hand by the breadth of the cleft 170, which in this example isapproximately 2 mm, as well as the height of the dam 190.

After the passage through the lysing device 100 the sludge exits inthickened form at the exit 195 of the lysing device 100.

According to FIGS. 3a and 3b the recesses 163 on the upper surface ofthe rotating grinding disk 161 are preferably constructed or designed asnotches in a radial direction, but can however, according to FIG. 3balso exhibit an angle of attack with respect to the radial direction.

In the example case it is particularly preferred, that the recesses 163are arranged to be staggered. This means, that adjacent lying notch rows141 are so arranged, that in regions in which the notch row 141 isinterrupted, the adjacent notch row 141 does not exhibit anyinterruption.

The advantage lies on the one hand in an elevated pumping effect and adevelopment of greater pressure gradient within the cleft 170, so thatoverall a noticeably increased lysing effect of the lysing device 100results.

In any case the lysing device according to FIG. 2 can include multiplelysing devices 100, so that a multi-step lysing device is provided,whereby the lysing effect is yet further significantly increased.

Of course the number of lysing device steps is limited by the necessaryenergy expenditure and the relationship to the bio-gas production, thatis to say, with other words, the energy requirement/notch-relationship.

Beyond this a sieve or filter step can be provided for retaining thelarger foreign bodies, which in certain cases could damage the lysingdevice 100, prior to entry of the sludge in the cleft 170 or also priorto the centrifuge entrance 8.

In FIG. 4 the lysing device 200 of the inventive device 1 is shown in asecond embodiment. The lysing device 200 is in this case constructed asa friction grinding unit, and more specifically as a milling cone 205.The rotating outer cone 220 of the milling cone 200 is connected withthe jacket 7 of the centrifuge 4. The grinding or milling surface 261 ofthe outer cone 220 is provided with recesses 263. In the case of theexample such recesses 263 are preferred, which are directed in thedirection of the jacket line of the milling cone 205. Fundamentally itis however also possible, that the recesses 263 are provided at an angleof attack to the jacket line of the milling cone 205. In exemplary casesthe recesses 263 are constructed as notches on the milling surface 261of the outer cone 220 in such a manner, that adjacent lying notch rowsare provided to be staggered, so that regions in which the notch rowsare interrupted, the adjacent notch row does not exhibit aninterruption.

Hereby similarly a better lysing effect is achieved.

Opposite to the rotating outer cone 220 lies a stationary inner cone230, which exhibits a milling surface 262. Between the inner cone 230and the outer cone 220 of the lysing device 200 there is a cleft 270, ofwhich the breadth can be changed via an adjustment device 275.

For improving the pumping effect and for the improved distribution ofthe sludge the depth of the recesses 263 are so selected in the case ofthe example that they correspond approximately with the breadth of therecesses 263. Particularly advantageous on a milling cone 205 as alysing device 220 of a device 1 for thickening of waste water sludgelies based therein, that with a lysing device 200 of this type in theform of a milling cone 205, foreign bodies in the sludge which enterinto the inside 250 of the milling cone 205 do not result in disruptionof the milling cone 205, but rather on the basis of a spring mounting276 can be received, so that a removal of foreign bodies by means of asieve or filter is not absolutely necessary. FIG. 5 shows as a lysingdevice 300 a profile rasp 305 as third illustrative embodiment of thedevice 1 of the present invention. The profile rasp 305 is comprised ofa rotating rasp surface 320 and a stationary outer shell 330. Therotating rasp surface 320 is connected with the jacket 7 of thecentrifuge 4. According to FIG. 5 the sludge is conveyed in thedirection indicated by the arrow through the screw gear or screwconveyor 6 as well as the rotating jacket 7 into the inside 350 of theprofile rasp 305 and passes out an exit opening 355 in the cleft 370between the rotating rasp surface 320 and the stationary rasp surface330 and is there squashed and milled, so that the cells contained in thesludge are lysed in the cleft 370 as a result of the high shear forcesand the high pressure within the cleft 370, whereby their cellularcontent is released into the surrounding medium.

For increasing the pressure within the cleft 370, in this example thepart 325 of the rotating milling surface 320 farthest away from the exit395 is inclined more strongly toward the outer jacket 330 and the part326 of the rotating milling surface 320 closest to the exit 395 is lessstrongly inclined towards the stationary milling surface 330 so that inthis area a broader cleft 370 results than on the other side from theexit opening 355. This plane or elevation which increases towards theoutside produces a significant pressure increase which has the effect ofincreasing the lysing effect of the lysing device 300.

In this embodiment it is preferable, so that practically no sealingproblems occur, to construct the embodiment of the lysing device in asimple manner, so that no metal rubbing occurs and that larger particlescan be diverted sidewards, so that as a rule no additional filteringmeans are necessary.

FIG. 6 shows a section along line 6--6 in FIG. 5. According to thisembodiment of the lysing device 300 the profile mill 305 (sic) exhibitson its rotating rubbing surface 320 wave shaped recesses 363, whichpreferably exhibit an angle of attack to the rotation of direction. Inan exemplary case the breadth of the cleft 370 in its narrowest point isapproximately 2 mm and its broadest point is approximately 10 mm.

In accordance with this embodiment the sludge is forced to flow throughthe narrow space between the stationary milling surface 330 and therotating rasp surface 320, which exhibits wave shaped recesses 320.Thereby a higher pressure results in the cleft 370 which causes such ahigh shearing force to result, that membrane and cell walls of themicroorganisms, in particular bacteria, are shredded and release theircytoplasm into the surrounding medium.

FIG. 7 shows as lysing device 400 a roller crusher 405 as a fourthembodiment of the present invention.

The rotating part 420 of the roller crusher 405 is connected with thejacket 7 of the centrifuge 4, so that it rotates along with it. Thelysing device 400 is closed off towards the outside with a stationarypart 430, but however exhibits an outlet opening 495 between therotating part 420 and the stationary part 430.

Both the rotating part 420 as well as the stationary part 430 exhibitopenings 421 and 431. In the openings 421 and 431 roller bodies, in thisexample rollers 440, are provided. In exemplary cases the lysing device400 exhibits two roller sets 441 and 442.

During rotation of the rotating part 420 of the roller crusher 405 therollers 440 move in the manner of a roller bearing between the rotatingpart 420 and the stationary part 430.

As a result of the movement of the jacket 7 and the screw conveyor 6 inthe direction indicated by the arrow according to FIG. 7, the sludgeenters from the centrifuge exit 9 of the centrifuge 4 into the inside450 of the roller crusher 405 as lysing device 400. Theorganism-containing purified sludge then passes through the exit opening455 between the rollers 440, so that the rollers 440 when in motionengage the sludge between each other, roller over and thereby squash itin such manner that the cells contained in the sludge are lysed.

The sludge which has been squashed and lysed in this manner is thenconveyed via cleft 470 to the next roller set 442, where it is newlyroller over and squashed by the orbiting rollers 440, so that even moreorganismic cells are disrupted, so that their cellular content isreleased to the environment.

The sludge processed with the roller crusher 405 finally leaves thelysing device 400 via its outlet opening 495 where the sludge then,according to need, is further processed.

A particular advantage of the present exemplary fourth embodiment of thedevice 1 for thickening of waste water sludge according to FIG. 7 isfounded therein, that various cleft gaps 470 can be employed and variousroller sizes can be utilized depending upon the lysing effect to beobtained, so that by varying the parameters the breadth of the cleft470, the size of the rollers 440, and the number of the roller sets 441,442, a precise adjustment of the lysing amount can be achieved.

It is of course also possible, to provide not shown recesses in theupper surfaces of the rollers 440, which can be provided both radially,as well also in the direction of the jacket line of the roller cylinder,and as well also with an angle of attack to the direction of rotation.

In FIG. 7a a sectional view along line 7--7 in FIG. 7 is shown through afirst roller set 441 and the exit opening 455.

In FIG. 8 there is shown as a lysing device 500 a passing drum 505according to a fifth embodiment of the present invention.

The passing drum 505 comprises a rotating part 520 and a stationary part530, which are sealed with respect to each other via seals 501.

On the inside 550 of the lysing device 500 there are provided passingelements 561, in exemplary cases in varying angles to each other.

As in the other embodiments the rotating part 520 is connected with thejacket 7 of the centrifuge 4.

As a result of the movement of the screw conveyor 6 as well as thejacket 7, the sludge is conveyed to the centrifuge exit 9 in thedirection shown in the arrow and it passes then through the exit opening555 into the inside 550 of the passing drum 505. Sludge and the thereincontained microorganisms, such as for example bacteria, are thensqueezed through the narrow cleft 570 between the stationary part 530and the passing elements 561, whereby high shear forces result, so thatbacteria and other microorganisms are shredded by this shear force andare thereby lysed, whereby their cellular content is released to thesurrounding medium.

The sludge processed in the lysing device 500 exits at the exit opening595 and can in suitable manner be further processed. FIG. 9 shows asection through the passing drum 505 according to line 9--9 in FIG. 8.

FIG. 10 shows as lysing device 600 a cutting unit 605 as sixthembodiment of the present device 1 for thickening of waste water sludge.The cutting unit 605 includes a rotating part 620 which is provided withcutting elements 661.

The rotating part 620 is connected with the jacket 7 of the centrifuge4. The stationary part 620 of the lysing device 600 includes cuttingelements 662, which fit within the cutting element 661. In the exemplarycase the cutting elements are provided as knives, wherein the knives arearranged both side-by-side as well as one behind the other, whereinpreferably an arrangement according to FIG. 12, which shows a sectionalong line 12--12 in FIG. 10, are provided in standard arrangement.

The rotation of the rotating part 620 of the cutting unit 605 occurs insuch a manner, that the individual cutting elements 661 and 662 do notcontact each other and exhibit a gap 670 there between, which isadjustable as needed.

As in the other embodiments the sludge is conveyed from the centrifuge 7to the centrifuge exit 9, which with a speed of approximately 50 m/s isconveyed to the inside 650 of the lysing device 600.

The sludge from the centrifuge 4 first meets the angled surface 651 ofthe stationary part 630. On the basis of this impacting of the clarifiedsludge already a number of the present microorganisms cells, such asbacteria and protozoa, rupture.

In order to further increase the lysing impact effect upon the angledouter surface 651, uneven features such as in the form of knives, pinsor the like can be provided.

The sludge is then conveyed via channel 652 to the actual cutting unit656. The knife shaped cutting elements 661 rotate in the exemplary casewith a rotating speed of approximately 80 m/s. The sludge is then passedthrough the cleft 670 between the knives 661 and 662 and must, in thepresent embodiment, pass by four rows of cutting elements 662, in orderto finally reach the sludge exit 695.

On the basis of the rotation speed as well as the design of the cuttingdevice 656 and the cutting elements 651 and 652 enormous shearing forcesinfluence on the microorganisms contained in the sludge, so that thelargest part of the therein contained microorganisms cells are shredded,whereby an extreme lysing effect is produced by the cutting unit 605,whereby the majority of the cells contained in the sludge are lysed andrelease their cytoplasma into the surrounding environment, in order toprovide an excellent nutritive medium for the surviving cells, whichthen lead to an increased bio-gas production and reduction of the amountof sludge.

FIG. 11 shows a section along lines 11--11 in 5 [sic] FIG. 10 from whichit can be seen, that in the lysing device 600 also cutting elements 661or 662 can be employed, of which the ends, in which the exemplaryembodiment are knife ends 663, are so designed, that a part of thesludge of the preceding knife part is again fed back or returned,whereby 10 [sic] a certain pumping effect in the direction of thecentrifuge results and whereby the shearing force and therewith thelysing effect can be increased even further.

At the exit 695 there is provided a dam 690, of which the height 15 isadjustable and therewith the residence time within the cutting device656 and therewith the lysing degree is adjustable.

FIG. 12 shows a section along line 12--12 in FIG. 10, from which it canbe seen, that the cutting elements 661 20 [sic] and 662 which areprovided in the cutting element or knife rows 641, are staggered withrespect to each other.

FIG. 13 shows a section view of a pin milling device 705 of a lysingdevice 700 of an inventive device 1 in a seventh embodiment.

The pin milling device is provided, as in the other illustrativeembodiments, as an integral component of the centrifuge 4 at thecentrifuge outlet 9. The lysing device 700 and in particular the pinmilling device 705 includes a rotating part 720 and a stationary part730. The stationary part 730 is sealed towards the outside with seals701.

The rotating part 720 is connected to the jacket 7 of the centrifuge 4.The rotating part 720 of the pin milling device 705 is provided withmultiple rows of pins 761, which engage in the entreaties formed by pins762 and which are provided on the stationary part 730.

In an exemplary case the rotating part 720 and the stationary part 730respectively each are provided with three pin rows 741.

The pin milling device 705 is closed off towards the outside by a dam790 and includes a sludge outlet 795.

As in the other embodiments the sludge is conveyed in the directionshown on the arrow through the centrifuge 4 to the centrifuge outlet 9and enters then into the inside 750 of the lysing device. The sludge isthen forced into the interstitial spaces 770 between the individual pins761 and 762 and is then subject to large shear forces produced by therotation of pins 761. Similarly to the cutting unit 605 of the lysingdevice 600, large shear forces occur in the pin milling device 705between the individual pins 761 and 762 or as the case may be betweenthe individual pin rows 741, which are capable of disrupting cells ofthe microorganisms contained in the sludge, so that their content isreleased to the surrounding medium.

The sludge processed with the lysing device 700 then exits throughsludge outlet 195 and can as desired be further processed.

The residence time of the sludge and therewith the amount of lysing canbe adjusted through the height of the dam 790.

In a preferred embodiment of the present pin milling device 705 thedistance or spacing between the two pin rows 741 is adjustable, wherebyan even greater shear effect can be produced and therewith a higherlysing level can be achieved.

FIG. 14 shows a section along line 14--14 in FIG. 13.

Particular advantages of the lysing device 700 in the form of a pinmilling device 705 lie founded therein, that the residence time isadjustable, the efficiency is easily adjustable for example by thenumber of pins 761 and 762 and that the individual pins 761, 762 caneasily be changed out as necessary.

A further advantage lies in the relatively small constructional spacerequirement and in relatively large tolerances for the individual pins.As desired it may be useful to provide at the centrifuge outlet 9 or atthe inlet to the centrifuge 4 a filter not shown in FIG. 13, in order toretain large foreign bodies, which might lead to damage of pins 761 and762.

Besides the high shear forces, which occur between the rows of pins 741,the lysing effect is made possible by impacting and battering the cells.

The purification unit shown in FIG. 15 for utilization of a waste waterclarification process includes a primary settling tank 802 with an inletor supply side 801 of raw waste water. The primary sludge 811 is thenconveyed to an anaerobic reactor 812. The effluent from the primarysettling tank 802 is conveyed to an aerobic biological activationsystem, the mixture from the activation system 803 is conveyed to asupplemental clarification tank 804, where a settling or separation outof the purified waste water 805 occurs. A part of the settled activatedsludge 806 is pumped back with a sludge return pump 820 as conveyancedevice in the activation system 803. The surplus activated sludge 807 isconveyed to a thickening centrifuge 4 with lysing device 10, wheresludge thickening as well as rendering or destroying of cells of aportion of the microorganisms occurs.

The centrate 809 is returned back to the activation system 803. Thethickened sludge is conveyed to the anaerobic reactor 812. A reactionmixture 813 from the anaerobic reactor 812 is conveyed to a thickeningor dewatering centrifuge 4a, where there occurs the dewatering of thestabilized sludge and the rendering or rupturing of cells of a portionof the microorganisms. The centrate 817 is returned back to theactivation system 803 and/or a part thereof is conveyed to the anaerobicreactor 812. The dewatered anaerobically stabilized sludge 815 passesvia outlet 818 to a dump and/or a part 816 thereof is returned back tothe anaerobic reactor 812.

The part of this system, in which the partial destruction of the cellsof the microorganisms occurs, is comprised of the thickening centrifuge4 and the dewatering centrifuge 4a and/or the return sludge pump 820 andthe above mentioned sludge pump. In an exemplary case the lysing deviceis provided as a friction grinding device 100 with a rotating grindingdisk 161 and a stationary grinding disk 162 at the centrifuge 4 while atthe outlet 9 of the centrifuge 4a a lysing device 10 in the form of aknife cutting unit 605 is provided.

For the preparation of the stimulating reagent it is also possible toemploy on the one hand activated sludge and on the other hand anaerobicstabilized sludge and more particularly either direct from the reactoron hand or from another, effective reactor. In the first indicated casethe surplus activated sludge 807 is conveyed to the thickeningcentrifuge 4 where there occurs, besides the thickening of the sludge, adestruction/lysing of part of the biomass cells in the lysing device,wherein the centrate 809 is returned to the activation device 803 andthe thickened part 810 is conveyed to the anaerobic reactor 812 forsludge stabilization. In the other case the anaerobic stabilized sludge813 is conveyed to the dewatering centrifuge 4a where besides thedewatering of the sludge there occurs a destruction of a part of thebiomass cells wherein a portion of 5 to 30% of the centrate 817 and/or apart of the 5 to 30% dewatered sludge 816 is returned back to theanaerobic reactor 812 for sludge stabilizing.

The treatment plant utilizing the process according to the presentinvention is thus significantly advantageous economically from theperspective of utilization at an the industrial scale in comparison tothe state of the art using a separate lysed preparation. In this mannerit is possible simultaneously to stimulate the aerobic and anaerobicbiological purification processes, and hereby to reduce the amount ofsludge to be disposed of and to increase the bio-gas production.

An application of the inventive device or, as the case may be, treatmentplant achieves in practice overall an improvement in a series oftechnical parameters. In the processing of dissolved impurities(anaerobic waste water purification), as well as the anaerobic sludgestabilization one reaches the following results: The output of theanaerobic reactor is increased, the decomposition of organic materialsis accelerated, the decomposition of organic materials in the course ofthe stabilization process is likewise accelerated (in sludge the depthof the anaerobic decomposition, in waste water the possibility ofdecomposing problematic materials such as, for example, variouszenobiotica or poisons), the bio-gas production is increased, theproduction of stabilized sludge is minimized, the dewatering ability ofthe anaerobic stabilized sludge is improved and the energy equation ofthe process in comparison to the conventional design is likewiseimproved.

EXAMPLE 1

The function as well as the technical utilization according to theinvention is to be seen in FIG. 15. As the main unit for preparation ofthe stimulating reagent, that is, for decomposing or the lysing of apart of the biomass cells of the overflow or surplus activated sludge, athickening centrifuge 4 is used. For determining the amount of releasedcell lysate the concentration of the released organismic substances,expressed as BOD₅ in the entrance stream 807 and the output stream 810from the thickening centrifuge 4 is used with the following results:

    ______________________________________                                        Inlet Stream (807)                                                                              BOD.sub.5(released)                                                                       -140 mg/l                                         Concentrate (Stream 810) BOD.sub.5(released) -630 mg/l                      ______________________________________                                    

With inlet stream 807 and concentrate 810 the tests of the methanogenicactivity was carried out. The concentration of the suspended materialswas adjusted such that it was the same in both streams. Tests werecarried out under the same conditions and with the same inoculumconcentration. As inoculum an anaerobic stabilized sludge from abioreactor was employed. The bio-gas production was determinedseparately for each stream and for the mixture of both streams with thesame amount of total mass. The bio-gas production of the same amount oftotal material was approximately 10.1% higher in the higher concentrate110 than by the inlet stream 807. The product results with the mixtureproduced an increase of approximately 13.3% and approximately 31.2% withrespect to the theoretical value depending upon the load of theanaerobic inoculum (0.54 and 0.27 g COD/g organic part in a gram of thenot dissolved material (a condition loss)). The theoretical valuepresents the sum of the production gas value of the same amount for eachstream individually.

EXAMPLE 2

Verification of the stimulation influence of the cell lysate on theanaerobic decomposition with simple substances.

Methanogenic activity tests of anaerobic co-fermentation with formicacid, vinegar, propionic acid and glucose were undertaken. In all casesthe same inoculum amount was employed, one test series was carried outwith addition of thickened surplus of activated sludge concentrate(stream 810) and another with addition of the same amount of inletsurplus activated sludge from the centrifuge (stream 807). Theco-fermentation of the complex materials with simple substratessometimes causes the increase of the decomposition ability of certaincomponents of the complex substrate. The co-fermentation of the sameamount of tested sludge with glucose exhibited an increase in thedecomposition ability with the inlet sludge to approximately 41.8% andwith the concentrate to approximately 51.3% (difference in effect ofapproximately 11.3%). The co-fermentation with formic acid was onlypositive at a concentration of 13.5% (difference in effect ofapproximately 33%).

What is claimed is:
 1. A thickening centrifuge for thickening of surplussludge (807), wherein said sludge contains organisms, and wherein alysing device is integrated in said thickening centrifuge (4) forrupturing cells of organisms contained in said sludge.
 2. A thickeningcentrifuge according to claim 1, wherein said lysing device comprises atleast one milling device and/or rasping device.
 3. A thickeningcentrifuge according to claim 2, wherein the thickening centrifuge (4)comprises a rotating conveyor device (6) which conveys the sludge to asludge outlet (9).
 4. A thickening centrifuge according to claim 3,wherein said rotating conveyor device (6) is a screw conveyor.
 5. Athickening centrifuge according to claim 3, wherein the thickeningcentrifuge (4) further comprises a rotating jacket (7), and wherein thejacket (7) and the conveyor device (6) rotate with different rotationalspeeds.
 6. A thickening centrifuge according to claim 2, wherein thethickening centrifuge (4) comprises a rotating jacket (7).
 7. Athickening centrifuge according to claim 2, wherein the thickeningcentrifuge (4) is a jet centrifuge or a jet separator.
 8. A thickeningcentrifuge for thickening of surplus sludge (807), wherein said sludgecontains organisms, wherein a lysing device is integrated in saidthickening centrifuge (4) for rupturing cells of organisms contained insaid sludge, and wherein the lysing device (10; 100; 200; 300; 400; 500;600; 700) is a friction grinding device (100; 200).
 9. A thickeningcentrifuge according to claim 8, wherein the friction milling device(100; 200) comprises at least one grinding disk (161, 162) having agrinding surface for grinding the sludge and cells of the organismscontained in the sludge.
 10. A thickening centrifuge according to claim9, wherein at least one of said grinding disks exhibits recesses (163)at its grinding surface (164, 165).
 11. A thickening centrifugeaccording to claim 10, wherein said recesses (163) exhibit an angle ofincidence with respect to the radial direction.
 12. A thickeningcentrifuge according to claim 10, wherein said recesses are groovesinterrupted by non-recessed regions in the grinding surface (164, 165),thereby forming radial groove rows.
 13. A thickening centrifugeaccording to claim 12, wherein adjacent groove rows are staggered sothat in regions, in which a groove row is interrupted, the adjacentgroove row does not exhibit an interruption.
 14. A thickening centrifugeaccording to claim 8, wherein a the friction milling device comprises arotating grinding disk (161) and a stationary grinding disk (162),wherein said rotating grinding disk (161) rotates together with thejacket (7) of the thickening centrifuge and against said stationarygrinding disk (162), and wherein the space (170) between the twogrinding disks (161, 162) is adjustable.
 15. A thickening centrifugeaccording to claim 14, wherein said space (170) between the two grindingdisks (161, 162) is adjustable in the range of approximately 0.5 to 5mm.
 16. A thickening centrifuge according to claim 14, wherein thelysing device has an inlet and an outlet, and wherein the lysing deviceis provided with a dam (190) at its sludge outlet.
 17. A thickeningcentrifuge according to claim 8, wherein the friction grinding device(100; 200) comprises a grinding cone (205) for grinding the sludge andcells of the organisms contained in the sludge.
 18. A thickeningcentrifuge according to claim 17, wherein the grinding cone (205)comprises a rotating outer cone (220) with at least one grinding surface(261) and an inner cone (230) which has at least one surface (262)opposing said outer cone grinding surface (261).
 19. A thickeningcentrifuge according to claim 18, wherein said inner cone (230) isstationary.
 20. A thickening centrifuge according to claim 18, whereinat least the rotating outer cone (220) has recesses (263) on itsgrinding surface (261).
 21. A thickening centrifuge according to claim20, wherein said recesses are notches, wherein the breadth of the notchis the same as the depth of the notch.
 22. A thickening centrifugeaccording to claim 21, wherein the notches are interrupted bynon-recessed areas of the grinding surface (261, 262).
 23. A thickeningcentrifuge according to claim 22, wherein adjacent lying notch rows arestaggered, so that in areas in which a notch row is interrupted, theadjacent notch row is not interrupted.
 24. A thickening centrifugeaccording to claim 22, wherein inner and outer cones (230, 220) arepositioned separated (270) with respect to each other, and wherein theseparation distance (270) is adjustable.
 25. A thickening centrifugeaccording to claim 24, wherein the separation distance (270) isadjustable during rotation or while stationary via a bearing surface(275) and springs.
 26. A thickening centrifuge for thickening of surplussludge (807), wherein said sludge contains organisms, wherein a lysingdevice is integrated in said thickening centrifuge (4) for rupturingcells of organisms contained in said sludge, and wherein the lysingdevice (10; 100; 200; 300; 400; 500; 600; 700) is constructed as aprofile rasp (305).
 27. A thickening centrifuge according to claim 26,wherein the profile rasp (305) comprises a stationary outer hull (330)and a rotating rasp surface (320), said rasp surface including agrinding surface, wherein the distance (370) between outer hull (330)and rasp surface (320) is adjustable.
 28. A thickening centrifugeaccording to claim 27, wherein the rotating rasp surface (320) isprovided with recesses (363).
 29. A thickening centrifuge according toclaim 28, wherein said recesses (363) are wave shaped recesses (363).30. A thickening centrifuge according to claim 28, wherein the recesses(363) exhibit an angle of incidence to the direction of rotation to theprofile rasp (305).
 31. A thickening centrifuge according to claim 27,wherein the lysing device has a sludge inlet and a sludge outlet, andwherein the grinding surface (305) of the profile rasp has a part (326)extending in the direction of the sludge outlet (395) and a part (325)extending in the opposite direction, wherein the part (326) extending inthe direction of the sludge outlet (395) exhibits a greater separationfrom the wall of the outer hull (330) than the part (325) extending inthe opposite direction.
 32. A thickening centrifuge according to claim27, wherein the distance (370) between the rasp surface (320) and outerhull (330) is minimally approximately 2 mm to maximally approximately 10mm.
 33. A thickening centrifuge according to claim 26, wherein theprofile rasp (305) includes a central inlet for sludge.
 34. A thickeningcentrifuge for thickening of surplus sludge (807), wherein said sludgecontains organisms, and wherein a lysing device is integrated in saidthickening centrifuge (4) for rupturing cells of organisms contained insaid sludge, wherein the lysing device (10; 100; 200; 300; 400; 500;600; 700) is constructed as a roller crusher (405).
 35. A thickeningcentrifuge according to claim 34, wherein the roller crusher (405)comprises an outer hull (430) having an inner wall, and at least oneroller set (441, 442) which rolls upon the inner wall of the outer hull(430).
 36. A thickening centrifuge according to claim 35, wherein saidouter hull is stationary.
 37. A thickening centrifuge according to claim35, wherein the roller set (441, 442) comprises at least ten rollers.38. A thickening centrifuge for thickening of surplus sludge (807),wherein said sludge contains organisms, wherein a lysing device isintegrated in said thickening centrifuge (4) for rupturing cells oforganisms contained in said sludge, and wherein the lysing device (10;100; 200; 300; 400; 500; 600; 700) is constructed as a passing drum(505).
 39. A thickening centrifuge according to claim 38, wherein thepassing drum (505) comprises a stationary outer hull and multiplepassing elements which rotate within a stationary outer hull.
 40. Athickening centrifuge according to claim 39, wherein the spacing (570)between the multiple passing elements and the inner wall of the outerhull (530) is adjustable.
 41. A thickening centrifuge for thickening ofsurplus sludge (807), wherein said sludge contains organisms, wherein alysing device is integrated in said thickening centrifuge (4) forrupturing cells of organisms contained in said sludge, and wherein thelysing device (10; 100; 200; 300; 400; 500; 600; 700) is constructed asa cutting unit (605).
 42. A thickening centrifuge according to claim 41,wherein the cutting unit (605) comprises rotating cutting elements (641)and stationary cutting elements, wherein the cutting elements (641)engage within each other without however touching each other.
 43. Athickening centrifuge according to claim 42, wherein the rotatingcutting elements (641) are rows of knives (641), and wherein thestationary cutting elements are rows of knives (641).
 44. A thickeningcentrifuge according to claim 43, wherein the knives (661, 662) rotatewith a speed of approximately 50-100 m/s.
 45. A thickening centrifugeaccording to claim 43, wherein the knife rows (641) comprise a pluralityof knives (661, 662), wherein adjacent situated knife rows are staggeredso that in the areas, in which a knife row (661, 662) is interrupted,the adjacent knife row (641) is not interrupted.
 46. A thickeningcentrifuge according to claim 43, wherein the knife rows (663) exhibitan angle of incidence to the rotation direction of the cutting unit(605).
 47. A thickening centrifuge according to claim 43, wherein thespacing (670), the height and the circumference position of the knivesof the stationary and the rotating knife rows (641) are adjustable. 48.A thickening centrifuge according to claim 42, wherein the device isprovided with a dam (690) at its sludge outlet (695).
 49. A thickeningcentrifuge according to claim 48, wherein the lysing device has an inletand an outlet, and wherein the height of the dam (690) is adjustable atthe sludge outlet (695).
 50. A thickening centrifuge for thickening ofsurplus sludge (807), wherein said sludge contains organisms, wherein alysing device is integrated in said thickening centrifuge (4) forrupturing cells of organisms contained in said sludge, and wherein thelysing device (10; 100; 200; 300; 400; 500; 600; 700) is constructed asa pin milling device (705).
 51. A thickening centrifuge according toclaim 50, wherein said lysing device has a sludge inlet and a sludgeoutlet, wherein the pin milling device (705) comprises rotating rows ofpins (761; 741) rotating about an axis, stationary rows of pins (762;741), as well as a dam (790) at the sludge outlet (795), wherein therotating and the stationary rows of pins (761, 741) engage within eachother without however contacting each other.
 52. A thickening centrifugeaccording to claim 51, wherein the space (770) between the stationaryand the rotating pins (761, 762) is adjustable.
 53. A thickeningcentrifuge according to claim 51, wherein the rotating pins (761) rotatewith a speed of approximately 50-100 m/s.
 54. A thickening centrifugeaccording to claim 51, wherein the rows of pins (761, 762) are arrangedsuch that adjacent situated pin rows (741) are staggered, such that inregions in which no pins are present in a pin row (741), the adjacentpin row (741) is provided with pins (761, 762).
 55. A thickeningcentrifuge according to claim 51, wherein the pins of the pin rows (761,762) are provided at an angle with respect to the axis of rotation. 56.A thickening centrifuge according to claim 51, wherein a dam (790) isprovided at the sludge outlet (795), and wherein the height of said dam(790) is adjustable at the sludge outlet (795).
 57. A process forminimizing the amount of decayed or residual sludge produced bytreatment plants, said process comprising the following steps:allowingwaste water to settle in at least one settling tank (802) to formsettled surplus sludge (807) and solids-reduced waste water; thickeningthe surplus sludge (807) from the settling tank (804) by passing throughat least one thickening centrifuge (4), wherein approximately 0.5 to 50%of the amount of the micro-organism cells originally contained in thesurplus sludge (807) are lysed in the thickening centrifuge (4) duringthe thickening; conveying the lysed thickened settled surplus sludge(807) to at least one anaerobic reactor (812) by means of at least oneconveyance device; anaerobic converting said thickened settled surplussludge (807) in said at least one anaerobic reactor (812); conveying thesolids-reduced waste water following settling to an aerobic activationdevice (803); and aerobic conversion of the solids-reduced waste waterin said at least one aerobic activation device (803).
 58. A processaccording to claim 57, wherein said anaerobic reactor (812) produces acombustible gas.
 59. A process according to claim 58, wherein saidcombustible gas is methane.
 60. A process according to claim 58, whereinsaid combustible gas produced in the process is used for production ofelectricity.
 61. A process according to claim 60, wherein theelectricity produced is employed for powering the treatment plant.
 62. Aprocess according to claim 58, wherein the thickening in the centrifugeand lysing in the lysing device act on the sludge and organisms tosynergistically increase the volume of gas produced in said step ofanaerobic conversion by 10-50%.